CN101908753B - Current differential protection method automatically adaptive to variable frequency motor - Google Patents
Current differential protection method automatically adaptive to variable frequency motor Download PDFInfo
- Publication number
- CN101908753B CN101908753B CN201010218574A CN201010218574A CN101908753B CN 101908753 B CN101908753 B CN 101908753B CN 201010218574 A CN201010218574 A CN 201010218574A CN 201010218574 A CN201010218574 A CN 201010218574A CN 101908753 B CN101908753 B CN 101908753B
- Authority
- CN
- China
- Prior art keywords
- current
- frequency
- variable
- differential
- frequency motor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Landscapes
- Control Of Ac Motors In General (AREA)
Abstract
The invention discloses a current differential protection method suitable for a variable frequency motor. Through HHT (Hilbert-Huang Transform), the amplitude and phase information of each frequency component of non-stable signals is acquired, the frequency component with the maximum energy (maximum amplitude) is selected as a main frequency of the signals, the actual running condition of the variable frequency motor is considered, the main frequency component is the main component of the signals and other frequency components can be regarded as harmonic components. The main frequency components subjected to HHT of three-phase current at the head and tail ends of the variable frequency motor are taken to calculate phasor differential to form the HHT-based differential protection principle. The current differential protection method can automatically adapt to the running conditions of the variable frequency motor under different frequencies, and avoids the problem that the traditional power frequency differential protection method cannot protect the variable frequency motor.
Description
Technical field
The invention belongs to relay protection of power system and technical field of automation, be specifically related to a kind of differential protecting method of adjustable frequency motor.
Background technology
Adopt the adjustable frequency motor of inverter supply to have comparatively wide in range frequency traffic coverage, conversion power supply has produced very big influence for the relaying protection of high-tension motor, especially the current differential protection as big capacity high motor main protection is had the greatest impact.Because conventional differential protection is based on power frequency 50Hz, can not correctly protect the high-pressure frequency-conversion motor of wide-range-timing.At present, on-the-spot taked certain interim measure when the converting operation for the motor that installs frequency converter additional: when running on the frequency conversion mode, for avoiding the motor differential protection malfunction appears, and the motor differential protection of correspondence is out of service; When running on the power frequency mode, again differential protection is put into operation.
Country's relaying protection rules regulation: capacity need be installed current differential protection as main protection at 2000kW and above motor; The motor of capacity below 2000kW should adopt current quick as main protection; When the current quick sensitivity coefficient does not meet the demands, should install current differential protection as main protection
According to afore mentioned rules, the high-pressure frequency-conversion motor is out of service with differential protection, is the regulation that does not meet national relaying protection rules.But traditional differential protection can't adapt to adjustable frequency motor, is very significant so research and development adapt to the differential protection of adjustable frequency motor.
Summary of the invention
The present invention provides a kind of current differential protection method that can be adapted to variable-frequency motor, and to overcome the deficiency of traditional power frequency differential protection, its step comprises:
A kind of differential protecting method of automatically adaptive to variable frequency motor different frequency operating mode; This differential protecting method carries out the calculating of differential current and stalling current according to variable-frequency motor machine end three-phase current and neutral point three-phase current; And then the current differential protection of formation phase-splitting; It is characterized in that said current differential protection method may further comprise the steps:
1) based on Hilbert transform HHT; Extract the amplitude and the phase information of each frequency component of three-phase current of variable-frequency motor machine end; Choose the wherein maximum signal basic frequency of frequency of energy; Calculate amplitude and the phase place of the dominant frequency component Im of three-phase current, said energy maximum is meant that this frequency component current amplitude is maximum;
2) extract amplitude and the phase place of the dominant frequency component In of variable-frequency motor neutral point place three-phase current according to said basic frequency;
3) adopt variable-frequency motor machine end three-phase current dominant frequency component Im and neutral point dominant frequency component In to carry out differential protection and calculate, adopt ratio-restrained characteristic to carry out fault distinguishing then,
Wherein, differential current Icd=|Im+In|, stalling current Izd=|In| adopts ratio-restrained characteristic to carry out fault distinguishing then, if (Izd Icd) is positioned at ratio-restrained characteristic top, thinks the inner failed because of variable-frequency motor, otherwise thinks there is not fault.
(Izd Icd) is the coordinate points that stalling current and differential current form, and the ratio-restrained characteristic of mentioning in the literary composition is exactly with stalling current and the differential current characteristic curve as abscissa and ordinate
The present invention can automatically adaptive to variable frequency motor in the running status of different frequency, avoided conventional power current differential protection when the variable-frequency motor converting operation, to protect the problem that withdraws from, improved the protective capability of variable-frequency motor.
Description of drawings
Fig. 1, variable-frequency motor current differential protection sketch map.
Embodiment
Below in conjunction with accompanying drawing and instance the present invention is done further detailed description.
Be illustrated in figure 1 as the variable-frequency motor current differential protection sketch map of inverter supply.Variable-frequency motor differential protecting method disclosed by the invention; This differential protecting method carries out the calculating of differential current and stalling current according to the three-phase current of variable-frequency motor machine end current transformer CT1 collection and the three-phase current of neutral point current instrument transformer CT2; And then the current differential protection of formation phase-splitting, when being judged to be motor fault, differential protection sends trip signal and gives circuit breaker; Cut off power supply; With reference to accompanying drawing 1,, introduce the wherein differential protection implementation method of a phase below because the present invention is the current differential of phase-splitting.Variable-frequency motor current differential protection method of the present invention may further comprise the steps:
1) utilizes the HHT conversion that the electric current of variable-frequency motor machine end is resolved into several intrinsic mode functions through empirical modal, utilize Hilbert transform structure analytic signal then, draw the instantaneous frequency and the amplitude of machine end electric current.
For current signal x (t), the analytic signal that can construct it is following:
X(t)＝x(t)+jH{x(t)}
H{x (t) wherein } be the Hilbert transform of signal x (t), that is:
Like this, we have just obtained the real part and the imaginary part of signal phasor, and then obtain the amplitude and phase place A (t) e of phasor
J θ (t), wherein
θ (t)=arctan (H{x (t) }/x (t)) calculates the rate of change of phase place again and then obtains the frequency information of this signal
Consider the practical operation situation of adjustable frequency motor, can think the main component of basic frequency composition seizing signal, other frequency components can be regarded as harmonic component.Choose the wherein signal basic frequency of frequency of energy maximum (being energy size judgment basis to the maximum) with amplitude;
This step can be obtained the phasor of the basic frequency composition of variable-frequency motor machine end CT1 place electric current, is designated as Im
2) repeat above-mentioned steps, extract amplitude and the phase place that the variable-frequency motor neutral point obtains the dominant frequency component of neutral point CT2 electric current, be designated as In according to basic frequency;
3) the variable-frequency motor both sides electric current basic frequency composition Im and the In that obtain according to step 1 and 2 carry out differential protection calculating.Differential current Icd=|Im+In|, stalling current Izd=|In| adopts ratio-restrained characteristic to carry out fault distinguishing then; If (Izd Icd) is positioned at the ratio-restrained characteristic top, thinks and breaks down; And send trip signal and give circuit breaker Q S, tripping circuit breaker Q S, isolated fault.Otherwise think and do not have fault.
Claims (1)
1. the differential protecting method of an automatically adaptive to variable frequency motor different frequency operating mode; This differential protecting method carries out the calculating of differential current and stalling current according to variable-frequency motor machine end three-phase current and neutral point three-phase current; And then the current differential protection of formation phase-splitting; It is characterized in that said current differential protection method may further comprise the steps:
1) based on Hilbert transform HHT; Extract the amplitude and the phase information of each frequency component of three-phase current of variable-frequency motor machine end; Choose the wherein maximum signal basic frequency of frequency of energy; Calculate amplitude and the phase place of the dominant frequency component Im of three-phase current, wherein, said energy maximum is meant that this frequency component current amplitude is maximum;
2) extract amplitude and the phase place of the dominant frequency component In of variable-frequency motor neutral point place three-phase current according to said basic frequency;
3) adopt variable-frequency motor machine end three-phase current dominant frequency component Im and neutral point dominant frequency component In to carry out differential protection and calculate, adopt ratio-restrained characteristic to carry out fault distinguishing then,
Differential current Icd=|Im+In|, stalling current Izd=|In| adopts ratio-restrained characteristic to carry out fault distinguishing then; If (Izd Icd) is positioned at ratio-restrained characteristic top, thinks the inner failed because of variable-frequency motor; Otherwise thinking does not have fault, wherein, and said (Izd; Icd) be the coordinate points that stalling current and differential current form, said ratio-restrained characteristic is with stalling current and the differential current characteristic curve as abscissa and ordinate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201010218574A CN101908753B (en) | 2010-07-06 | 2010-07-06 | Current differential protection method automatically adaptive to variable frequency motor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201010218574A CN101908753B (en) | 2010-07-06 | 2010-07-06 | Current differential protection method automatically adaptive to variable frequency motor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN101908753A CN101908753A (en) | 2010-12-08 |
| CN101908753B true CN101908753B (en) | 2012-10-03 |
Family
ID=43264122
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201010218574A Active CN101908753B (en) | 2010-07-06 | 2010-07-06 | Current differential protection method automatically adaptive to variable frequency motor |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN101908753B (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102323477A (en) * | 2011-06-09 | 2012-01-18 | 南京信息工程大学 | Method and apparatus for measuring interhamonics of power grid |
| CN102623960B (en) * | 2012-04-12 | 2014-02-05 | 台州发电厂 | Variable-frequency motor protection device based on intelligent sensors |
| CN103051282A (en) * | 2012-08-23 | 2013-04-17 | 上海外高桥第二发电有限责任公司 | Variable-frequency and industrial frequency switching device and switching method of Variable-frequency and industrial frequency switching device |
| CN106786385B (en) * | 2016-12-13 | 2019-01-18 | 南京国电南自电网自动化有限公司 | A kind of differential protecting method being suitable for adjustable frequency motor |
| CN107181237B (en) * | 2017-07-07 | 2018-11-13 | 南京南瑞继保电气有限公司 | A kind of pump-storage generator Back To Back Startup Procedure differential protecting method and system |
| CN108092234B (en) * | 2017-12-28 | 2019-12-24 | 长园深瑞继保自动化有限公司 | Differential protection method and device suitable for variable frequency motor |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1632997A (en) * | 2005-01-14 | 2005-06-29 | 北京四方继保自动化股份有限公司 | Anti-TA transient imbalance differential protection for generator |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2510681C (en) * | 2005-06-28 | 2007-03-20 | Vassili Rozine | Device and a method for advanced protection from short circuit current |
-
2010
- 2010-07-06 CN CN201010218574A patent/CN101908753B/en active Active
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1632997A (en) * | 2005-01-14 | 2005-06-29 | 北京四方继保自动化股份有限公司 | Anti-TA transient imbalance differential protection for generator |
Non-Patent Citations (6)
| Title |
|---|
| 同步电动机变频发电对保护配置的要求及实现;周正权等;《水电自动化与大坝监测》;20090420;第33卷(第2期);第32-35页 * |
| 周正权等.同步电动机变频发电对保护配置的要求及实现.《水电自动化与大坝监测》.2009,第33卷(第2期),第32-35页. |
| 唐红键等.大容量高压电动机变频器继电保护对策探讨.《电力建设》.2010,第31卷(第5期),第81-85页. |
| 大容量变频器对电动机继电保护的影响;张超等;《继电器》;20070901;第35卷(第17期);第9-11页 * |
| 大容量高压电动机变频器继电保护对策探讨;唐红键等;《电力建设》;20100531;第31卷(第5期);第81-85页 * |
| 张超等.大容量变频器对电动机继电保护的影响.《继电器》.2007,第35卷(第17期),第9-11页. |
Also Published As
| Publication number | Publication date |
|---|---|
| CN101908753A (en) | 2010-12-08 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101908753B (en) | Current differential protection method automatically adaptive to variable frequency motor | |
| CN101577417B (en) | Method for current differential protection of direct current electric transmission line | |
| CN105140897B (en) | A kind of guard method suitable for small resistance grounding system singlephase earth fault | |
| CN102723735B (en) | Island detection method and system | |
| CN103257298B (en) | Based on the combining inverter island detection method of parameter adaptive Sandia frequency deviation method | |
| CN102255293A (en) | Single-ended electrical quantity full-line quick-action protection method for recognizing faults inside and outside high-voltage direct-current transmission line region | |
| CN102590691A (en) | Method for detecting internal and external faults of ultra high voltage direct current transmission lines based on pole wave mathematical morphology spectrum | |
| CN103560517B (en) | Doubly-fed wind generator low voltage ride through method | |
| Yang et al. | High-frequency fault component-based distance protection for large renewable power plants | |
| CN102062831A (en) | Single-phase permanent fault recognition method for extra-high voltage AC transmission line | |
| CN201125843Y (en) | Lightning protection protective system of wind generating set | |
| Zheng et al. | High-frequency fault analysis-based pilot protection scheme for a distribution network with high photovoltaic penetration | |
| CN102522733B (en) | HVDC power-transmission whole-line speed protection method by using direct-current filter current | |
| CN103532113A (en) | Rapid distance protection method for power transmission line containing micro-grid system | |
| Jia et al. | Amplitude comparison based pilot protection for renewable power teed line | |
| Han et al. | An improved pilot protection for distribution network with inverter-interfaced distributed generations | |
| CN110048372B (en) | Improved high-voltage generator stator single-phase earth fault protection method | |
| CN103592569B (en) | A kind of extra-high-voltage direct-current transmission line fault location based on high frequency content attenuation characteristic | |
| CN104362640B (en) | Reactive power control method in wind power plant | |
| CN100424956C (en) | Fault tolerant re-judging negative sequence direction locking type longitudinal zero voltage inter-turn protection for generator | |
| CN100557915C (en) | Serial compensation capacitance directional impedance protection method based on voltage compensation | |
| CN105846459B (en) | The adaptive distance protection method combined based on intrinsic frequency with characteristic frequency | |
| CN209881381U (en) | Circuit breaker protection module with direct current and broadband measurement function | |
| Oliveira et al. | Magnification of transients at the voltage dips starting and its impacts on DFIG-based wind power plants | |
| Cao et al. | Research on main transformer protection of doubly-fed wind farm based on fault current frequency difference |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant |